{"id":80,"date":"2025-10-21T04:36:18","date_gmt":"2025-10-21T04:36:18","guid":{"rendered":"https:\/\/codetypingpro.com\/?p=80"},"modified":"2025-12-17T07:48:35","modified_gmt":"2025-12-17T07:48:35","slug":"lesson-18-iterators-and-generators-in-python","status":"publish","type":"post","link":"https:\/\/codetypingpro.com\/?p=80","title":{"rendered":"Lesson 18: Iterators and Generators in Python"},"content":{"rendered":"\n

\ud83c\udfaf Lesson Objective<\/strong><\/h3>\n\n\n\n

To understand how iterators and generators<\/strong> work in Python for efficient data traversal and memory management.<\/p>\n\n\n\n

\n\n\n\n

\ud83e\udde9 1. What Is an Iterator?<\/strong><\/h2>\n\n\n\n

An iterator<\/strong> is an object that can be iterated (looped) over<\/strong>.
It implements two methods:<\/p>\n\n\n\n

    \n
  • __iter__()<\/code> \u2192 returns the iterator object itself<\/li>\n\n\n\n
  • __next__()<\/code> \u2192 returns the next value<\/li>\n<\/ul>\n\n\n\n

    \u2705 Example: Using Iterator on a List<\/strong><\/p>\n\n\n\n

    numbers = [1, 2, 3, 4]\nit = iter(numbers)\n\nprint(next(it))  # 1\nprint(next(it))  # 2\nprint(next(it))  # 3\nprint(next(it))  # 4\n# print(next(it))  # Raises StopIteration\n<\/code><\/pre>\n\n\n\n
    \n\n\n\n
    \ud83d\udd04 2. Iterating Using a Loop<\/strong><\/h2>\n\n\n\n
    numbers = [5, 10, 15]\nfor num in numbers:\n    print(num)\n<\/code><\/pre>\n\n\n\n
    Output:<\/strong><\/p>\n\n\n\n
    5\n10\n15\n<\/code><\/pre>\n\n\n\n
    \n
    Python\u2019s for<\/code> loop automatically uses iterators.<\/p>\n<\/blockquote>\n\n\n\n
    \n\n\n\n
    \ud83e\uddf0 3. Creating a Custom Iterator<\/strong><\/h2>\n\n\n\n
    class MyRange:\n    def __init__(self, start, end):\n        self.current = start\n        self.end = end\n\n    def __iter__(self):\n        return self\n\n    def __next__(self):\n        if self.current > self.end:\n            raise StopIteration\n        val = self.current\n        self.current += 1\n        return val\n\nnums = MyRange(1, 5)\nfor n in nums:\n    print(n)\n<\/code><\/pre>\n\n\n\n
    Output:<\/strong><\/p>\n\n\n\n
    1\n2\n3\n4\n5\n<\/code><\/pre>\n\n\n\n
    \n\n\n\n
    \ud83e\uddf1 4. What Is a Generator?<\/strong><\/h2>\n\n\n\n
    A generator<\/strong> is a special function<\/strong> that yields values one by one<\/strong>, saving memory for large sequences.<\/p>\n\n\n\n
    \u2705 Example: Generator Function<\/strong><\/p>\n\n\n\n
    def my_generator(n):\n    for i in range(1, n+1):\n        yield i\n\ngen = my_generator(5)\nfor val in gen:\n    print(val)\n<\/code><\/pre>\n\n\n\n
    Output:<\/strong><\/p>\n\n\n\n
    1\n2\n3\n4\n5\n<\/code><\/pre>\n\n\n\n
    \n\n\n\n
    \ud83d\udd04 5. Generator Expressions<\/strong><\/h2>\n\n\n\n
    Similar to list comprehensions but use parentheses<\/strong> and generate values on the fly.<\/p>\n\n\n\n
    squares = (x**2 for x in range(1, 6))\nfor val in squares:\n    print(val)\n<\/code><\/pre>\n\n\n\n
    Output:<\/strong><\/p>\n\n\n\n
    1\n4\n9\n16\n25\n<\/code><\/pre>\n\n\n\n
    \n\n\n\n
    \ud83d\udee0\ufe0f 6. Advantages of Generators<\/strong><\/h2>\n\n\n\n
      \n
    • Memory efficient \u2192 generate items one at a time<\/strong>.<\/li>\n\n\n\n
    • Can handle large datasets<\/strong>.<\/li>\n\n\n\n
    • Useful for pipelines and streaming data.<\/li>\n<\/ul>\n\n\n\n
      \u2705 Example: Fibonacci Generator<\/strong><\/p>\n\n\n\n
      def fibonacci(n):\n    a, b = 0, 1\n    for _ in range(n):\n        yield a\n        a, b = b, a + b\n\nfor num in fibonacci(10):\n    print(num)\n<\/code><\/pre>\n\n\n\n
      Output:<\/strong><\/p>\n\n\n\n
      0\n1\n1\n2\n3\n5\n8\n13\n21\n34\n<\/code><\/pre>\n\n\n\n
      \n\n\n\n
      \ud83c\udf0d 7. Real-Life Example \u2013 Reading Large File<\/strong><\/h2>\n\n\n\n
      def read_file_line_by_line(filename):\n    with open(filename, \"r\") as file:\n        for line in file:\n            yield line.strip()\n\nfor line in read_file_line_by_line(\"example.txt\"):\n    print(line)\n<\/code><\/pre>\n\n\n\n
        \n
      • Only one line is in memory at a time<\/strong>, efficient for large files.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"
        \ud83c\udfaf Lesson Objective To understand how iterators and generators work in Python for efficient data traversal and memory management. \ud83e\udde9 1. What Is an Iterator? An iterator is an object that can be iterated (looped) over.It implements two methods: \u2705 Example: Using Iterator on a List \ud83d\udd04 2. Iterating Using a Loop Output: Python\u2019s for […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6,1],"tags":[],"class_list":["post-80","post","type-post","status-publish","format-standard","hentry","category-python-easy-course-outline","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/codetypingpro.com\/index.php?rest_route=\/wp\/v2\/posts\/80","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/codetypingpro.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/codetypingpro.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/codetypingpro.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/codetypingpro.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=80"}],"version-history":[{"count":1,"href":"https:\/\/codetypingpro.com\/index.php?rest_route=\/wp\/v2\/posts\/80\/revisions"}],"predecessor-version":[{"id":81,"href":"https:\/\/codetypingpro.com\/index.php?rest_route=\/wp\/v2\/posts\/80\/revisions\/81"}],"wp:attachment":[{"href":"https:\/\/codetypingpro.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=80"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/codetypingpro.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=80"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/codetypingpro.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=80"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}